This invention relates to cyanoacrylate adhesive compositions which are improved in toughness by incorporation therein of selected polyester polymers.
Cyanoacrylate compositions are well known as excellent adhesives. Known advantages for these compositions are they can be used as a single component, are convenient and easy to use since they cure rapidly at room temperature without an external energy source and they have the ability to bond a wide variety of substrates making them useful in numerous bonding operations. Despite these attributes, cyanoacrylate adhesives do have their limitations and one primary shortcoming is in the area of impact resistance and toughness.
Attempts to change and improve the properties of cyanoacrylate compositions have included the addition of various thickeners, fillers, toughening agents and other modifiers and additives. U.S. Pat. No. 4,102,945 discloses a cyanoacrylate adhesive composition thickened by a copolymer or terpolymer resin capable of being dissolved or solvated by the cyanoacrylate monomer and resulting in significantly improved peel strength.
U.S. Pat. No. 4,105,715 discloses a cyanoacrylate adhesive composition which is made thixotropic by incorporating powdered organic fillers such as polycarbonate, polyvinylidene fluoride, polyethylene and acrylic block copolymer resins containing saturated elastomer segments.
U.S. Pat. No. 4,425,471 involves cyanoacrylate adhesive compositions containing an alkyl 2-cyanopenta-2,4-dienoate which have improved resistance to heat and water and exhibit suitable peel and impact strengths.
U.S. Pat. No. 4,440,910 discloses cyanoacrylate adhesive compositions containing elastomeric polymers such as acrylic rubbers as fillers and exhibit substantially increased toughness.
U.S. Pat. No. 4,560,723 discloses a cyanoacrylate adhesive composition containing a toughener such as a core-shell thermoplastic/rubber copolymer which is treated to remove impurities which cause premature polymerization of cyanoacrylates and a compatible organic compound having one or more aryl groups, such as diphenylmethane, to provide improved retention of peel strength and toughness.